fix libgnunetutil check

configure.ac

@@ -29,39 +29,31 @@ AC_SEARCH_LIBS([gcry_check_version], [gcrypt], [], [AC_MSG_ERROR([unable to find
 AC_CHECK_HEADER(gcrypt.h, [], [AC_MSG_ERROR([unable to find the gcrypt.h header file from libgcrypt])], [])
 
 SAVE_LIBS=$LIBS
-gnunetutil=0
-AC_MSG_CHECKING(for libgnunetutil)
-AC_ARG_WITH(gnunetutil,
-   [  --with-gnunetutil=PFX   base of libgnunetutil installation],
-   [AC_MSG_RESULT([$with_gnunetutil])
-    case $with_gnunetutil in
-      no)
-        ;;
-      yes)
-        AC_CHECK_HEADERS(gnunet/gnunet_util_lib.h,
-          AC_CHECK_LIB([gnunetutil], [GNUNET_CRYPTO_ecc_dlog],
-            gnunetutil=1))
-        ;;
-      *)
-        LDFLAGS="-L$with_gnunetutil/lib $LDFLAGS"
-        CPPFLAGS="-I$with_gnunetutil/include $CPPFLAGS"
-        AC_CHECK_HEADERS(gnunet/gnunet_util_lib.h,
-          AC_CHECK_LIB([gnunetutil], [GNUNET_CRYPTO_ecc_dlog],
-            EXT_LIB_PATH="-L$with_gnunetutil/lib $EXT_LIB_PATH"
-            gnunetutil=1))
-        ;;
-    esac
-   ],
-   [AC_MSG_RESULT([--with-gnunetutil not specified])
-    AC_CHECK_HEADERS(gnunet/gnunet_util_lib.h,
-     AC_CHECK_LIB([gnunetutil], [GNUNET_CRYPTO_ecc_dlog],
-      gnunetutil=1))])
-if test x$gnunetutil = x1
-then
- AC_MSG_RESULT([libgnunetutil found])
-else
- AC_MSG_ERROR([libbrandt requires libgnunetutil])
-fi
+
+AC_MSG_CHECKING([for libgnunetutil])
+AC_ARG_WITH(gnunet,
+            [AS_HELP_STRING([--with-gnunet=PFX], [base of GNUnet installation])],
+            [AC_MSG_RESULT([given as $with_gnunet])],
+            [AC_MSG_RESULT(not given)
+             with_gnunet=yes])
+AS_CASE([$with_gnunet],
+        [yes], [],
+        [no], [AC_MSG_ERROR([--with-gnunet is required])],
+        [LDFLAGS="-L$with_gnunet/lib $LDFLAGS"
+         CPPFLAGS="-I$with_gnunet/include $CPPFLAGS"])
+AC_CHECK_HEADERS([gnunet/platform.h gnunet/gnunet_util_lib.h],
+ [AC_CHECK_LIB([gnunetutil], [GNUNET_SCHEDULER_run], libgnunetutil=1)],
+  [], [#ifdef HAVE_GNUNET_PLATFORM_H
+        #include <gnunet/platform.h>
+       #endif])
+AS_IF([test $libgnunetutil != 1],
+  [AC_MSG_ERROR([[
+***
+*** You need libgnunetutil to build this program.
+*** This library is part of GNUnet, available at
+***   https://gnunet.org
+*** ]])])
+
 # restore LIBS
 LIBS=$SAVE_LIBS